An integrated circuit may include multiple transistor die that are placed in an integrated circuit package by a die attach machine. A robotic bonding tool may be used to wire bond the die to a package substrate, leads of a package leadframe, or other circuit elements within the package. Such a tool generally includes a surface/wire-feed detection system that detects bond pads or other bond sites of a given die. The other circuit elements in an integrated circuit may include, for example, tuning capacitors.
The wire bonding of the various circuit elements may create several differently-shaped wire bond profiles, depending on the placement of the various circuit elements to be connected by wire bonds. A wire bond profile may be characterized as a side or profile view of a wire extending from a first bond site to a second bond site. In an integrated circuit, the wire bonds may carry high frequency signals. It is important for these wire bond profiles to achieve a desired shape for optimal high speed data signal performance, for example at least approximately 2.5 Gb/s.
The wire bonds of an integrated circuit are typically parallel to one another in a plan view of the integrated circuit. This parallel configuration results in a high level of mutual coupling between neighboring wire bonds. Thus, wire bonds packed tightly together result in a substantial mutual coupling. As the mutual coupling increases, the stability of the electrical performance and operating bandwidth decreases. The noise generated by crosstalk in each interface may result in bit errors that limit the system data throughput.
Previous attempts to solve the problem of mutual coupling include increasing the pitch of, or distance between, wire bonds at bond sites on the die. While increased distance between wire bonds assists in decreasing the mutual coupling between wire bonds, the number of wires that can be bonded to the die is decreased, resulting in an integrated circuit with a smaller overall number of wire bonds. Other attempts to reduce crosstalk between adjacent wire bonds include increasing the distance between wire bonds at the bond sites, or wedge bonds, on a substrate of the integrated circuit package. However, this also increases substrate size and resulting package size, which is directly proportional to cost. Flip chip technology has also been provided and recommended to those customers seeking a high speed device since many do not believe that a wire-bond package is capable of performing at desired high speeds.
Thus, a need remains for techniques for minimizing mutual coupling between wire bonds and the associated degradation of high speed signals in an integrated circuit.